The joining of electronic packaging subcomponents, such as die attachment, typically employs soldering. Soldered joints are often favored because they can be easily-processed at temperatures below the tolerable levels for semiconductor devices, particularly those of silicon. However, soldering uses metal alloys that unlike most pure metals, have relatively low electrical and thermal conductivities. They are also prone to fatigue and failure due to intermetallic compound formation and phase separation, which cause deformations leading to bonding caused failures such as crack initiation during temperature cycles. Furthermore, only a few solder alloys have high enough melting points to potentially work above 250° C. and those that do are much more expensive than ordinary solder.
With the commercial availability of wide-bandgap semiconductor devices such as SiC or GaN, there is an increasing need for higher temperature die attachment processes since solder alloys do not provide the adequate high-temperature performance and reliability.